[CentOS] reboot - is there a timeout on filesystem flush?

I've had a few systems with a lot of RAM and very busy filesystems
come up with filesystem errors that took a manual 'fsck -y' after what
should have been a clean reboot.  This is particularly annoying on
remote systems where I have to talk someone else through the recovery.

Is there some time limit on the cache write with a 'reboot' (no
options) command or is ext4 that fragile?

-- 
   Les Mikesell
     lesmikesell at gmail.com